Cutting tool



- Aug. 18,1942.

W. L. BOND CUTTING *rooL Filed Feb. .2, 1940 lNl/ENTOR WL. BOND BYATTORNEY Patented Au 18, 1942 UNITED STATE CUTTING TOOL Walter L.Boilfl, SoutlrOra'nge, N. 1., assignor to Bell Telephone Laboratories,

Incorporated,

New York, N.,Y., a corporation of New York Application Febrnary z, 1940,Serial No. 316,946 2 Claims. -(Cl. 125-13) This invention relates to acutting tool and more particularly to a'saw for cutting Rochelle saltand similar brittle, water "soluble; materials.

An object of the invention is to facilitate cutting Rochelle salt andsimilar materials.

A more specific object of the invention is to prevent the accumulationon the edge of the blade of particles of the material being cut.

In the preparation of Rochelle salt plates,

which have been utilized for some time as piezoelectric elements inelectrical circuits such as oscillators and filters and which have morerecently been proposed for use in electrical relays,

,as disclosed, for example, in Patent 2,166,763,

issued July 18, 1939, to W. P. Mason, it is the usual practice to cut anumber of relatively thin, substantially flat, plates or slabs from alarger crystal.

Various methods and means have been proposed in the past for cuttingthese thin plates including the wet-string" cutter, the "mud saw andsawsutilizing toothed blades; none of these has, however, in applicant'sexperience, been entirely satisfactory. In some instances the operationhas been entirely too slow to be commercially feasible, in others it hasbeen practically impossible to produce plates of the desiredthinness andwith the necessary high degree of plane parallelism, while in stillother instances excessive breakage of the fragile material has re--sulted.

In the case of the so-called mud saw. which commonly comprises a thindisc of steel or copper rotating in-aliquid, such as water, containingabrasive, it is applicant's belief that unsatisfactory cutting ofRochelle salt and similar is broken away. l

A further feature of the invention is an abrasive. carrying liquid whichdoes not tend to cause cooling of the material being out due toevaporation. v

A still further feature of the. invention is means for stabilizing thedisc whereby lateral displacement during cutting is prevented.

In accordance with a specific embodiment of the invention, a metal disc,for example, of steel or copper, is provided which is rotatedcomparatively slowly, for example, at a speed of revolutions per minute.in an abrasive liquid which comprises abrasive particles carried inkerosene. Means are provided for supporting the material to be cut incontact with the cutting edge of the disc. A metal roller, for exampleof hard steel. is rotatably supported in contact with the edge of thedisc. Contact of the cutting edge of the disc with the roller iseffective to break away any accumulation which tends to become glazed onthe cutting edge of the disc. While thedisc, of c0urse.'does tend tocutinto the roller, this cutting is very slow due both to the hardness ofthe roller and to the fact that it is rotatably supported with respectto the disc wherebya new point of contact is constantly presented. Theroller is Preferably provided with a groove in which the edge of thedisc rides; the walls of the groove, which is just slightly wider thanthe disc, are effective to prevent any'lateral displacement of the discduring cutting.

A thorough understanding of the arrangement contemplated by the presentinvention as well as appreciation of the'various desirable featuresthereof may be' gained from consideration of the following detaileddescription and the accompanying drawing in which:

Fig. 1 is a view in perspective of a cutting tool which embodiesfeatures in accordance with the present invention; and

Fig. 2 is a plan view of a portion of the tool showing particularly theposition of the roller with respect to the cutting edge of the disc.

Referring now to Fig. 1, driving motor II is shown mounted on .platforml2. Also mounted on platform I2 are upright supporting members [3 andI4. Pulley-wheel i5 is attached to one end of a shaft (not shown) whichis rotatably positioned in a transverse housing provided in the upperportion of support l3; cutting disc I6 is attached to the other end ofthe shaft. Disc I6 is of relatively thin metal, for example it may be ofNo. 16 to No. 20 gauge steel or coppenand is preferably provided withtwo reinforcing flanges; one of these flanges l'l, being shown and thesecond, which is similar to flange ll and mounted on the opposite faceof disc it, not being shown.

A tank 2| is supported from upright member it by bracket members 22 and23; this tank serves as a container for the abrasive liquid, preferablykerosene carrying abrasive particles.

Also supported from upright member 13, by'

means of a third bracket member 24, is table 25 which'serves as asupport for the material being cut.

Dash-pot 4| is mounted on upright member M by means of bracket member42. A hard steel roller 43 is rotatably supported by bracket 44 which isattached to the end of piston rod 45 of the dash-pot.

As shown more clearly in Fig. 2, roller 43 is provided with twocircumferential grooves El and 52, the roller being shown in theposition whereinthe cutting edge of disc I6 is positioned in groove ii.In order to bring about engagement of the edge of disc l6 and groove 52,it is merely necessary, first, to remove tank 2| by emoval of the boltsutilized in attaching brackets 22 and 23 to member l3, and then toremove disc it from the shaft, pull bracket 44 and pistonrod 4! forwarda suiilcient distance to permit disengagement of positioning pin 53 fromthe aperture provided near the left-edge of upturned portion 54 ofbracket 42 and rotate piston rod 45 and bracket 44 one-half turnwhereupon pin 53 may be engaged with a suitable aperture (not shown)provided'near the right edge of upturned portion 54 of bracket 42. DiscIt may now be replaced on the shaft, roller 43 now being in positionwherein the edge of disc It will be positioned in groove 52.

In order to further describe the arrangement, let us assume that a slabis to be sawed from Rochelle salt crystal H which is shown in positionon table 25. Pulley-wheel l5 and the driving-wheel of motor II' arecoupled by a suitable belt 12 so that, as motor II is set intooperation, pulley-wheel I5 is rotated in the direction indicated by thearrow. This motion is, of course, transmitted to-disc II by theconnecting shaft so that disc It now rotates in the same direction aspulley-wheel ii; the rate at which disc I8 is rotated should preferablybe relatively slow, for example in the neighborhood of 150 revolutionsper minute.

Tank 2| is filled with the abrasive mixture, preferably kerosene ca yingabrasive particles, to a sumcient level to insure that a substantialportion of disc I6 is submerged in the liquid at all times. As the discrotates, portions of the abrasive cling to the edge of the disc and arecarried around to the sawing point where they the thin hard edge of discIt. The use of kerosene rather than liquids used heretofore,particularly water, has proven advantageous as evaporation is avoided;evaporation is objectionable as the resulting cooling of the Rochellesalt causes excessive breakage of the fragile material. Further, theRochelle salt is not dissolved or otherwise affected deletericusly bythe kerosene.

It has previously been observed by applicant that when saws of thisgeneral nature have been used for cutting Rochelle salt crystals, asalty accumulation tends to become glazed on the cutting edge of thedisc and that the rate of cutting is reduced thereby to anunsatisfactory I degree. In the instance of the saw of the presentinvention, howeverfengagement oi the edge of disc I 8 with the hardsteel roller 43 is effective to break away this brittle glazed coatingbefore it can build up sufliciently to be at all objectionable. Whileengagement of the roller with the edge of the disc tends to break awaythe brittle coating of salt accumulation, it tends, on-the contrary, toforce the abrasive particles carried by the disc into somewhat moreintimate contact with the disc material than would be achieved in theabsence of the roller.

' As illustrated, roller 43 is provided with two circumferential grooves5| and 52, the edge of disc It being shown positioned in groove ll. jEngagement of the edge of the disc with the defining walls of groove 5|is effective to prevent any lateral displacement, or wobbling," of discit.

While the material of roller 43 is itself out by disc it, this cuttingtakes place very slowly due to the hardness of roller 43, the fact thatthe invention is not, of course,

' are effective in furthering the cutting effect of roller is rotatablymounted, and the fact that the dash-pot mounting permits the roller tomomentarily "back away from the disc in the event of any undueobstruction. If groove II becomes deepened to an undesirable; extent,the roller assembly may be rotated as described above to a positionwhere the edge of disc I. will be engaged by groove 52. Upon occasionthe roller may be replaced by a new one.

While a specific embodiment of the invention has been selected fordetailed description. the

so limited in its application. The embodiment taken as illustrative ofthe invention and not as restrictive thereof.

What is claimed is:

1. In a tool for cutting relatively thin slabs from a Rochelle saltcrystal, a relatively thin rotatable disc. means for supporting theRochelle salt crystal in position to be cut by said disc, a roller of amaterial harder than Rochelle salt,

and means for rotatably supporting said roller in contactwith thecutting edge of said disc during the cutting process, the material ofsaid roller being softer than said cutting edge whereby a relativelythin slot is cut in said roller by said disc.

2. In a tool for cutting relatively thin slabs from a body of brittle,water soluble material, a relatively thin rotatable disc, means forsupporting said body in position to be cut by said disc, a roller of amaterial harder than that of' said disc. I

WALTER L. BOND.

described should be

